Wiremu Curtis accepted that his actions undoubtedly contributed to Nia Glassie's death but he was not a murderer, a jury in the High Court at Rotorua was told this afternoon.
Defence lawyer Craig Horsley said the "frightful" treatment of Nia at her home in July last year by 18-year-old Curtis - partner of the three-year-old's mother - was "totally unacceptable" even if labelled as rough games or a joke.
Wiremu Curtis had not intended to hurt Nia and what he did was stupid but not criminal.
Mr Horsley said Curtis was only 17 at the time "a slow learner with the academic ability of a 12-year-old".
He was easily intimidated and "a follower, not a leader".
Curtis wasn't thinking of the consequences of his actions and had no murderous intent, the lawyer said.
"It just didn't cross his mind."
Earlier in the day Jonathan Temm, counsel for Wiremu's older brother Michael Curtis, 22, opened the defence case in the trial of the five people charged over Nia's death.
The brothers are both accused of murder, while Nia's mother Lisa Kuka, 35, cousin Michael Pearson, 20, and Michael Curtis's partner Oriwa Kemp, 18, face manslaughter counts.
Mr Horsley said it was understandable if jurors were disgusted, loathed his client and felt someone must pay for what happened to little Nia Glassie.
"But to decide he is guilty based on those feelings would be wrong. This is a court of law and the decision must not be based on moral outrage."
Incidents such as the toddler being put on a revolving clothes line had started as a game - one in which Wiremu Curtis was "merely a spectator", Mr Horsley submitted.
Michael Curtis had been the one who pushed the line harder and faster until Nia fell off.
Putting her in a tumble dryer also began as a "silly, idiotic game" that was taken too far without any consideration of the consequences.
He said throwing a basketball at Nia and wrestling her were naive teenage games "as outrageous as it might be, as mind blowingly stupid as it might be".
Curtis did not act with malice. When she was hurt or cried, he stopped.
"His game playing went awry. The fact that this may be morally stupid behaviour does not elevate it up the ladder to criminal behaviour," Mr Horsley said.
Like Mr Temm, he suggested the Friday night kicks to Nia's head, which the Crown says led to her death, did not happen.
Rather, the little girl had begun a gradual decline two days earlier after she fell two metres to the ground off the clothesline. That incident may have resulted in a subdural haematoma. Or, according to expert witnesses, it could have even happened 12 to 16 days earlier.
The youngster had suffered numerous "not insignificant" bangs to the head over some days, which could have caused a cumulative effect, Mr Horsley said.
Her lethargy, sleepiness and complaints of a sore head earlier on the Friday - before the prosecution claims the kicks to the head happened - were consistent with her suffering a head trauma and the bleeding to the brain that led to coma and eventual death.
Mr Horsley told the jury that, just because both Curtis brothers were charged with murder, they did not have to find both guilty.
"Murder requires murderous intent. Manslaughter does not."
Unless jurors were sure, they must not convict Wiremu Curtis of murder "no matter how much you want to do so" because it would be wrong in law.
Lawyers for Pearson, Kemp and Kuka will address the jury tomorrow.
The month-long trial is expected to end early next week.
